MS has officially stated that Internet Explorer 9 will be released on March 14 at SXSW http://news.cnet.com/8301-13577_3-20041126-36.html. It appears from the RC documentation that there will be a compatiblity mode to show you how IE 8 and possibly IE 7 will render the page http://support.microsoft.com/kb/956197 Windows XP users won't be able to upgrade but frankly it is past time to get off XP in my opinion if you have any concern about security. We've got Win 7 running on netbooks faster than they ever ran XP.

With IE 8 being the second browser to fall in this year's PWN2OWN (3 hours, first was OS X/Safari where it took 5 sec to find the exploit and an hour to write the tools/test suite to prove it up) folks will be encouraged to upgrade quickly. MS usually starts pushing their new browsers via Windows updates within a month or two of release. For people running the beta version the RC was available on Windows Update so who knows how quickly they'll start pushing IE 9 out that way.